Pressure activated IV set

ABSTRACT

An IV set includes a drip chamber and a pressure activated valve. The drip chamber has an operable liquid height and an outlet orifice. The pressure activated valve is disposed proximate the outlet orifice of the drip chamber and includes a sealing orifice, a valve, and a biasing mechanism. The sealing orifice and the operable liquid height correspond to a head. The biasing mechanism biases the valve against the sealing orifice with a force less than the head of the operable liquid height to control the flow of liquid through the pressure activated valve.

CROSS-REFERENCED RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 60/654,705, filed Feb. 18, 2005.

BACKGROUND OF THE INVENTION

This invention relates generally to tubing sets used in the administration of liquids to a patient that are commonly referred to as intravascular (“IV”) sets and more particularly concerns pressure activated IV sets. An IV set according to the invention is used broadly herein to include tubing sets used in the arterial, intravenous, intravascular, peritoneal, and non-vascular administration of liquid into a patient. Of course, one of skill in the art may use an IV set to administer liquids to other locations within a patient's body than those listed.

Generally, an IV set includes tubing for connecting a patient to a source of liquid. Additionally, an IV set may include a drip chamber connected to the tubing, which is used by a nurse, physician, or other attendant to determine the flow rate of liquid through the IV set. The drip chamber is shaped to encourage liquid entering the drip chamber to form droplets that fall toward the bottom of the drip chamber. By counting each droplet over a period of time, the flow rate of liquid is able to be discerned.

When an IV set is prepared for use with a patient, a clamp on the tubing is manually closed to prevent liquid from moving from the drip chamber through the tubing. The IV set may then be attached to a source of liquid, such as an IV bag or bottle. Once attached, the drip chamber is squeezed to force air out of the drip chamber which is replaced by liquid from the IV bag or bottle.

Generally, enough air is removed to permit the drip chamber to be filled about ⅓ to about ½ full of liquid, which may be deep enough to prevent air in the drip chamber from being sucked into the tubing. Additionally, this liquid height is also low enough that each droplet may be efficiently counted by an attendant. To obtain this liquid height, the drip chamber may need to be squeezed repeatedly and closely monitored to obtain an operable liquid height.

Once the height of the liquid in the drip chamber is sufficient for operation of the IV set, the clamp is manually opened to allow liquid to flow through and replace air in the tubing of the IV set. However, as the liquid flows through the tubing air is frequently trapped in the tubing. For example, the flow of the liquid through the tubing of the IV set may be turbulent and can entrap air as the boundary layer between the liquid and the tubing is sheared. Additionally, if the liquid level is too low, a bubble ladder may form as air is intermittently sucked from the drip chamber into the tubing.

Once the liquid is distributed throughout the tubing of the IV set, it is a generally good practice to remove entrapped air from the IV set. While this concern is critical when accessing allowed to enter a patient's blood stream while receiving the intravenous administration of liquids, the air bubbles can form an air embolism and cause serious injury to a patient.

To remove air bubbles from the IV set, liquid from the IV bag or bottle is allowed to flow through the tubing while an attendant taps the tubing to encourage the air bubbles out the end of the IV set. As the liquid is allowed to flow out of the IV set to clear air bubbles from the tubing, the liquid is generally allowed to flow into a waste basket or other receptacle. During this procedure the end of the tubing may contact the waste basket or be touched by the attendant and thus, become contaminated.

Once the entrapped air is removed, the IV set is ready to be connected to a patient. This process of preparing an IV set for connection to a patient is commonly referred to as “priming” an IV set.

If there is a delay between priming the IV set and connecting it to a patient, a solid cap may be attached to the end of the IV set to completely close and protect the end of the IV set from contamination. The cap may then be removed when the patient is ready to have the IV set connected.

Because of the constant supervision and many different steps that may be required to prime an IV set, the priming of an IV set may be a time consuming process. Additionally, the priming of an IV set can lead to the contamination of the IV set by inadvertently touching a sterile end of the IV set. Furthermore, the attention and time used to prime of an IV set could have been used to perform other tasks that may be valuable to the patient.

An additional concern may arise when the IV bag or bottle begins to run dry. Specifically, when the IV bag or bottle is empty, air may be pulled through the IV set and into the patient. To prevent air from entering a patient through an IV set, air bubble sensors may be connected to the IV set that alert an attendant that air has entered the IV set and is moving toward the patient. However, these sensors merely alert the attendant that action is required and do not act to prevent the air from entering the patient. Additionally, these sensors may be expensive and may require additional training to use.

Alternatively, a floating seal may be positioned in the drip chamber of an IV set. As the liquid level drops, the floating seal may be seated against the outlet orifice of the drip properly, which may allow air to enter a patient. Alternatively, the floating seal may be inadvertently sucked onto the outlet orifice of the drip chamber before the IV bag or bottle has run dry, preventing the patient from receiving needed liquid and medication.

Thus, an IV set may require frequent supervision by an attendant to avoid these problems. Furthermore, because air may enter the tubing in both of these options for preventing air from entering a patient through the IV set, the IV set may need to be debubbled as each used IV bag or bottle is replaced.

Accordingly, a need exists for an IV set that is self-priming, and which does not require constant attention and supervision. A need also exists for an IV set that is self-leveling to ensure that an operable liquid height is maintained in the drip chamber. Additionally, a need exists for an IV set that prevents air from entering the tubing when the IV bag or bottle runs dry.

BRIEF SUMMARY OF THE INVENTION

The apparatus of the present invention has been developed in response to the present state of the art, and in particular, in response to the problems and needs in the art that have not been fully solved by currently available IV sets. Thus, the present invention provides a pressure activated IV set for use in intravenous administration of liquids that may be self-priming and self-leveling.

In accordance with the invention as embodied and broadly described herein in the preferred embodiment, an IV set is provided. The IV set may include a coupling for connecting it to a source of liquid. The coupling may be a Luer fitting, a spike, or other coupling known in the art.

A drip chamber may be connected to the coupling for determining the flow rate of liquid through the IV set. Typically, IV sets are gravity fed so that the drip chamber may include an inlet orifice disposed in a top end and an outlet orifice disposed in a bottom end of the drip chamber. A sidewall may extend between the top end and the bottom end.

A pressure activated valve may be connected to the outlet orifice of the drip chamber that may control the flow of liquid through the outlet orifice of the drip chamber. In some configurations, the pressure activated valve may abut or be integrally formed with the drip chamber. The pressure activated valve may operate so that when an operable liquid height in the drip chamber is reached, the pressure activated valve opens to permit liquid to exit the outlet orifice of the drip chamber. Additionally, when the liquid height falls below the operable liquid height, the pressure activated valve closes to prevent liquid from exiting the outlet orifice of the drip chamber.

The pressure activated valve may include a sealing orifice that may be positioned inline with the outlet orifice of the drip chamber and may be integrally formed with the drip chamber. The sealing orifice may be a hole surrounded by a relatively sharp shoulder against which a valve may be seated to close the sealing orifice. Alternatively, the sealing orifice may include a beveled shoulder to encourage a tight seal with the valve.

The valve may have a shape similar to the shape of the sealing orifice to facilitate closing the sealing orifice. For example, the valve may have a rounded or beveled engagement surface for abutting and closing the sealing orifice. In some configurations, the valve may also include a flexible engagement surface that facilitates the sealing of the valve against the sealing orifice. Thus, the valve may include an elastomeric surface for providing a tight seal against the sealing orifice.

The pressure activated valve may also include a means for biasing and positioning the valve against the sealing orifice. The biasing means may be a biasing mechanism that stores potential energy such as a spring, a magnet, or a flexible arm. For example, the biasing mechanism may be a coil spring attached to the valve. The coil spring is compressed so that it applies a force to the valve against the sealing orifice. Alternatively, the biasing mechanism may be a magnet positioned to repel a second magnet attached to the valve so that the magnet of the biasing mechanism forces the valve against the sealing orifice.

In other configurations, the biasing mechanism may be a compliant arm attached to the valve that may be deflected to bias the valve against the sealing orifice. Alternatively, the biasing mechanism may include a torsion spring or leaf spring connected to a rigid arm attached to the valve that biases the valve against the sealing orifice. The biasing mechanism may also be an elastomeric material that when elastically compressed acts as a spring, which biases the valve against the sealing orifice.

The biasing mechanism may bias the valve against the sealing orifice with a force approximately equal or less than the pressure head between the sealing orifice and an operable liquid height in the drip chamber to control the flow of liquid through the pressure activated valve. Thus, as the pressure of the liquid above the valve exceeds the force of the biasing mechanism and/or any buoyancy forces associated with the valve, the valve is forced away from the sealing orifice to open the pressure activated valve. The weight of the valve and biasing mechanism may also be considered in determining the proper biasing force of the biasing mechanism. For simplicity, the force of the biasing mechanism generally includes any buoyancy forces associated with the biasing mechanism and the valve.

The operable liquid height is the height of liquid from the sealing orifice to a height within the drip chamber. More specifically, the operable liquid height within the drip chamber is such that if the drip chamber is held vertically and the IV set is filled with liquid to the operable liquid height, the liquid would exert a force against the valve greater than the force that the biasing mechanism biases the valve against the sealing orifice and any buoyancy forces associated with the valve and biasing mechanism.

Additionally, the operable liquid height may be approximately the height of liquid at which the drip chamber is normally filled when the IV set is ready to be connected to a patient. Thus, the operable liquid height may range from about ¼ to about ⅔ the height of the drip chamber. Preferably, the operable liquid height may range from about ⅓ to about ½ the height of the drip chamber.

When priming the IV set, liquid may be unable to enter the drip chamber from a source of liquid as the pressure within the drip chamber increases. To release this pressure, the drip chamber may include an air vent. The air vent may be designed to prevent liquid from passing through the vent, while allowing air to exit the drip chamber. The air vent may also permit air to only exit and not to enter the drip chamber. Additionally, the air vent may be connected to a sidewall of the drip chamber proximate to the operable liquid height. This helps to maintain a desirable liquid level within the drip chamber, by preventing additional air from exiting the drip chamber once liquid reaches the air vent.

Referring back to the IV set, the IV set may include a tube having a first end and a second end that may be connected to the pressure activated valve. The first end may include a coupling, such as a Luer fitting to facilitate connecting the IV set to a patient.

An end plug may be connected to the coupling of the first end of the tube. The end plug may include an air vent designed to permit air to exit and prevent liquid from exiting. The end plug may help to prevent contamination of the IV set and may be removed and discarded when the IV set is to be connected to a patient.

The air vent of the end plug may be used to slow the rate at which air exits the IV set. By slowing the exit of air from the IV set, liquid flowing through the IV set is also slowed. Slow flowing liquid is less likely to entrap air in the IV set, which reduces the need to remove air bubbles from the IV set.

Additionally, the IV set may include a means for disposing the first end of the tube proximate the drip chamber. The disposing means may be used to further slow the flow of liquid through the IV set by using hydrostatic pressure. The disposing means may also be used to prevent contamination of the remote end of the tube and to prevent liquid from inadvertently exiting the IV set.

The disposing means may be a tube attachment device. The tube attachment device may be integrally formed with the drip chamber, the pressure activated valve, or another part of the IV set. Of course, the tube attachment device may be formed separately. In some configurations, the tube attachment device may include a clip for positioning the remote end of the tube near the drip chamber, and more preferably, near the operable liquid height of the drip chamber. The tube attachment device may also include a magnet for magnetically positioning and securing the remote end of the tube near the drip chamber.

Alternatively, the tube attachment device may include a hook and loop fastener. For example, a piece of fabric having a plurality of hooks may be attached proximate the remote end of the tube and a piece of fabric having a plurality of corresponding loops may be attached to the drip chamber, the pressure activated valve, an opposite end of the tube, or another component of the IV set. Additionally, the tube attachment device may include an adhesive for positioning and securing the remote end of the tube near the drip chamber.

A method for priming the IV set disclosed above may include the steps of connecting the IV set to a source of a liquid, drawing the liquid into the drip chamber, and moving the valve from the sealing orifice to permit the liquid to exit the pressure activated valve when the head of the liquid in the drip chamber exceeds the force of the biasing mechanism. All of these steps may be accomplished automatically by the IV set of the invention except for connecting the IV set to a source of a liquid, which can result in considerable time savings for a physician, nurse, or attendant priming the IV set for use with a patient. Of course, the step of drawing liquid into the drip chamber may be facilitated by the nurse or attendant by squeezing the drip chamber to induce a vacuum into the drip chamber.

The method may also include the steps of disposing the remote end of the tube proximate to the drip chamber and preferably, near the operable liquid height of the drip chamber. In configurations where the IV set includes an air vent, the method also include the steps of venting air from the drip chamber and preventing air from exiting the air vent when the height of the liquid within the drip chamber reaches the height of the air vent. To prevent air from reaching a patient when the IV bag or bottle is empty, the method may also include the step of moving the valve against the sealing orifice to prevent the flow of liquid through the pressure activated valve when the head of the liquid within the drip chamber is less than the force of the biasing mechanism.

These and other features and advantages of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

In order that the manner in which the above-recited and other features and advantages of the invention are obtained will be readily understood, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the invention and are not therefore to be considered to be limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:

FIG. 1 is a perspective view of an IV set according to the invention connected to an IV bag;

FIG. 2 is a partially cut away side view of another IV set according to the invention connected to an IV bottle;

FIG. 3 is a partially cut away side view of an alternative IV set according to the invention;

FIG. 4 is a partially cut away side view of yet another IV set according to the invention; and

FIG. 5 is a partially cut away side view of yet another IV set according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

The presently preferred embodiments of the present invention will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout. It will be readily understood that the components of the present invention, as generally described and illustrated in the figures herein, could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of the embodiments of the IV set of the present invention, as represented in FIGS. 1 through 5, is not intended to limit the scope of the invention, as claimed, but is merely representative of presently preferred embodiments of the invention.

Referring to FIG. 1, a perspective view illustrates an IV set 10 connected to a source of liquid 12, such as an IV bag 14 containing a liquid 16, by a coupling 20. The coupling 20 may be a spike 22 that is used to puncture the IV bag 14 and access the liquid 16.

The coupling 20 of the IV set 10 may be connected directly to a drip chamber 24. More specifically, the coupling 20 may be connected to a top end 26 of the drip chamber 24. The top end 26 of the drip chamber 24 may include an inlet orifice 28 that receives liquid 16 from the IV bag 14 through the coupling 20.

The drip chamber 24 may include a sidewall 30 that extends between the top end 26 and a bottom end 32 having an outlet orifice 34. The sidewall 30 may include an air vent 36 that permits air to exit the drip chamber 24 while preventing liquid 16 from exiting the drip chamber 24 through the outlet orifice 34.

The air vent 36 prevents pressure from building in the drip chamber 24 with each droplet of liquid 16 that enters from the IV bag 14 when the flow of liquid 16 through the outlet orifice 34 is blocked. Without the air vent 36, pressure builds within the drip chamber 24 which may cause the flow of liquid 16 to slow until liquid 16 no longer enters the drip chamber 24. Thus, the air vent 36 may be positioned in the sidewall 30 to encourage the liquid 16 to fill to a desired height in the drip chamber 24. Specifically, the liquid 16 is encouraged to enter the drip chamber 24 up to the height of the air vent 36 in the side wall 30. Once the height of the liquid 16 reaches and blocks the air vent 36, the flow of liquid 16 slows and may stop entering the drip chamber 24 until flow through the outlet orifice 34 is unblocked.

To control the flow of liquid 16 through the outlet orifice 34, the outlet orifice 34 may be connected to a pressure activated valve 38. More specifically, the pressure activated valve 38 is disposed so that a sealing orifice 40 is in liquid communication with the outlet orifice 34 of the drip chamber 24. To block the flow of liquid 16 through the outlet orifice 34, a valve 42 may be moved against the sealing orifice 40 by a biasing mechanism 44.

The valve 42 may have a rounded engagement surface 46 that engages and abuts a sharp shoulder 48 of the sealing orifice 40. The engagement surface 46 may be flexible to provide a tight seal against the sealing orifice 40. For example, the valve 42 may be made of an elastomeric material that flexes to seal against the shoulder 48 of the sealing orifice 40.

The pressure activated valve 38 opens and closes in response to the height of liquid 16 being greater than or less than an operable liquid height 50, respectively. Specifically, the biasing mechanism 44 biases the valve 42 against the sealing orifice 40 with a force equal to about the head between the sealing orifice 40 and an operable liquid height 50 in the drip chamber 24 when the drip chamber 24 is held vertically. Thus, as the height of liquid 16 in the drip chamber 24 exceeds the operable liquid height 50, the pressure of the liquid 16 exceeds the biasing force of the biasing mechanism 44 to move the valve 42 away from the sealing orifice 40 and permit the flow of liquid 16 through the outlet orifice 34 of the drip chamber 24 and the pressure activated valve 38. When the height of liquid 16 in the drip chamber 24 is less than the operable liquid height 50, the pressure of the liquid 16 is less than the biasing force of the biasing mechanism 44. Therefore, the valve 42 engages and seals against the sealing orifice 40 preventing the flow of liquid 16 through the outlet orifice 34 of the drip chamber 24 and the pressure activated valve 38.

The biasing mechanism 44 in this configuration of the invention may include a spring 51. When the pressure activated valve 38 is assembled, the spring 51 may be attached to the valve 42 and compressed to store potential energy and bias the valve 42 against the sealing orifice 40.

Alternatively, the biasing mechanism 44 may include a portion of the valve 42 that is buoyant. Additionally, the spring 51 may tend to pull the valve 42 away from the sealing orifice 40. However, in this configuration, the biasing mechanism 44 is able to bias the valve 42 against the sealing orifice 40 because the buoyancy force of the portion of the valve 42 is greater than the force of the spring 51.

The pressure activated valve 38 may be connected to a tube 52 for conveying the flow of liquid 16 from the drip chamber 24. Specifically, the tube 52 may have a first end 54 and a second end 56 that may be connected to the pressure activated valve 38.

The first end 54 may have a connector 58 for connecting the IV set 10 to a patient (not shown), another IV set (not shown) in a piggy back arrangement, or another device known in the art. For example, the connector 58 may be connected to an end plug 60 that may be solid or include an air vent 62 that permits air to exit the tube 52 but prevents liquid 16 from exiting the first end 54 of the tube 52. The air vent 62 may also be designed to restrict the flow of air out of the first end 54 of the tube 52 in order to slow the flow of liquid 16 that moves through the IV set 10 when the IV set 10 is primed. The connector 58 may be Luer fitting for a threaded or press fit connection or another connector known in the art.

The IV set 10 may also include a tube attachment device 64 for disposing the second end 56 of the tube 52 proximate to the drip chamber 24 during priming of the IV set 10. Disposing the second end 56 of the tube 52 proximate to the drip chamber 24 during priming slows the flow of liquid 16 through the IV set 10 via the hydrostatic pressure of the liquid 16. As shown, the tube attachment device 64 may be integrally formed with the pressure activated valve 38 and may include a clip 66 for removable attachment of the tube 52 to the tube attachment device 64.

Referring to FIG. 2, a partially cut away side view illustrates another IV set 100 that may be connected to a source of liquid 102, such as an IV bottle 104 containing a liquid 106. the IV set 100 includes many features similar to the IV set 10 of FIG 1. For brevity similar features may not be discussed in detail.

As shown, a pressure activated valve 110 is open because the height of the liquid 106 in a drip chamber 112 exceeds the operable liquid height 114 of the drip chamber 112. Thus, the liquid 106 is able to flow from the drip chamber 112 through the pressure activated valve 110 to a tube 116.

The pressure activated valve 110 may include a housing 120 that defines a sealing orifice 122 in liquid communication with an outlet orifice 124 of the drip chamber 112. The sealing orifice 122 may include a beveled shoulder 126 that may be engaged by a valve 128 to close the sealing orifice 122. The valve 128 may have an engagement surface 130 that is reciprocally shaped to the shape of the sealing orifice 122 to facilitate engaging and closing the sealing orifice 122. Thus, the engagement surface 130 may be beveled.

The housing 120 further defines a flow chamber 132 that extends from the sealing orifice 122 to an exit orifice 134 that may be connected to the tube 116. The housing 120 may also include a support feature 136 for positioning a biasing mechanism 138 within the flow chamber 132. Specifically, the support feature 136 may extend into the flow chamber 132 to position the biasing mechanism 138 in line with the sealing orifice 122.

The biasing mechanism 138 may include a base magnet 140 that repels a valve magnet 142. The valve magnet 142 is a part of the valve 128 and attached to the engagement surface 130. The pressure activated valve 110 may be opened when the pressure of the liquid 106 exceeds the magnetic force between the opposed base magnet 140 and the valve magnet 142.

The IV set 100 may also include a tube attachment device 144 that may include two clips 146 for gripping a first end 148 and a second end 150 of the tube 116. The tube attachment device 144 may be used to position the first end 148 of the tube 116 near the drip chamber 112.

FIG. 3 is a partially cut away side view showing an alternative IV set 200. The IV set 200 includes many features similar to the IV set 10 of FIG. 1. For brevity, similar features may not be discussed in detail.

As shown, a pressure activated valve 202 is open because the height of the liquid 204 in the drip chamber 206 exceeds the operable liquid height 208. Because the pressure activated valve 202 is open, liquid 204 may flow from a drip chamber 206 and pass through the pressure

The pressure activated valve 202 may have a housing 211 that includes a sealing orifice 212 that is in liquid communication with an outlet orifice 214 of the drip chamber 206. The sealing orifice 212 may have a curved shoulder 216 that mates with a curved engagement surface 218 of a valve 220 of the pressure activated valve 202. The valve 220 is positioned and supported by a biasing mechanism 222.

The biasing mechanism 222 comprises arms 224 that may be attached to the housing 211. The arms 224 may be flexible so that the arms 224 bias the valve 220 toward the sealing orifice 212. The flexible arms 224 may be similar to a spring that stores potential energy as they flex in response to the head between the sealing orifice 212 and the height of the liquid 204 in the drip chamber 206, such that the valve 220 may move away from the sealing orifice 212 when the height of the liquid 204 exceeds the operable liquid height 226 of the drip chamber 206.

The IV set 200 may also include a tube attachment device 230. The tube attachment device may include a hook and loop fastener 232 for disposing a first end 234 of the tube 210 proximate to the drip chamber 206. As shown, a fabric strip of hooks 236 may be attached to the drip chamber 206 and a fabric strip of loops 238 may be connected to the first end 234 of the tube 210 to facilitate the positioning of the first end 234 of the tube 210 near the drip chamber 206.

FIG. 4 is a partially cut away side view illustrating yet another IV set 300. The IV set 300 includes many features similar to the IV set 10 of FIG. 1. For brevity, similar features may not be discussed in detail.

As shown in FIG. 4, an outlet orifice 302 of a drip chamber 304 is connected to a pressure activated valve 306. The pressure activated valve 306 is closed, because the height of a liquid 308 in the drip chamber 304 has not equaled or exceeded the operable liquid height 310. Therefore, the liquid 308 is unable to flow through the outlet orifice 302 of the drip chamber 304.

The pressure activated valve 306 includes a housing 312 that includes a sealing orifice 314 that has a sharp shoulder 316. An engagement surface 318 of a valve 320 may engage the shoulder 316 and close the sealing orifice 314.

As shown, the valve 320 may be integrally formed with a biasing mechanism 322. The valve 320 and biasing mechanism 322 may be an arm of elastomeric material that extends between the sealing orifice 314 and a support feature 324 of the housing 312. In some configurations, the valve 320 and biasing mechanism 322 may be made of a closed cell, foamed material or a solid material. Additionally, the valve 320 and biasing mechanism 322 may be made of an elastomer or other material known in the art.

As the height of the liquid 308 increases in the drip chamber 304, the biasing mechanism 322 compresses under the pressure of the liquid 308 in the drip chamber. When the liquid 308 is about equal to or exceeds the operable liquid height 310, the engagement surface 318 disengages from the sealing orifice 314 and the liquid 308 is able to flow through the outlet orifice 302 of the drip chamber 304 and the housing 312 of the pressure activated valve 306. Once the height of the liquid 308 falls below the operable liquid height 310, the biasing mechanism 322 expands to force the engagement surface 318 against the shoulder 316 of the sealing orifice 314 and close the pressure activated valve 306.

The IV set 300 may also include a tube attachment device 324 for disposing a first end 326 of a tube 328 near the drip chamber 304. A second end 330 of the tube 328 may be connected to the pressure activated valve 306. The tube attachment device 324 may include a first magnet 332 attached to the drip chamber 304 and a second magnet 334 attached to the first end 326 of the tube 328. Thus, to position the first end 326 of the tube 328, the first magnet 332 may be brought near the second magnet 334.

In reference to FIG. 5, a partially cut away side view illustrates a different IV set 400 according to the invention. The IV set 400 is similar in many ways to the IV set 300 of FIG. 4. Thus, for brevity, only the differences will de discussed detail. As shown, the IV set 400 includes a pressure activated valve 402 disposed between a drip chamber 404 and the tubing 406 of the IV set 400. Specifically, an outlet orifice 408 of the drip chamber 404 is connected to a sealing orifice 410 of a housing 412 of the pressure activated valve 402. The housing 412 of the pressure activated valve 402 also includes an exit orifice 410 that is connected to the tubing 406.

The housing 412 contains a structure 414 that includes the biasing mechanism 416 and valve 418 of the pressure activated valve 402. The housing 412 includes a wall 420 that is disposed at an angle 422 to the sealing orifice 410. The angle 422 of the wall 420 guides the valve 418 as it moves within the housing 412 to seat against the sealing orifice 410 and close the pressure activated valve 402.

The biasing mechanism 416 of the structure 414 is total volume of the structure 114 having an average density less than water. As shown in a partially cut away view, the average density less than water may be obtained by including one or more air bubbles 424 within the structure 414, by making the structure 414 out of a material 426 whose density is less than the density of water, or a combination of these methods. The valve 418 is the outer surface 428 of the structure 414 that contacts and seats against the sealing orifice 410 to close the pressure activated valve 402.

The pressure activated valve 402 operates by initially allowing fluid to pass through the pressure activated valve 402. As the housing 412 fills with liquid, the structure 414 floats upward to seat against the sealing orifice 410 and close the pressure activated valve 402. Thus, the valve 418 is held against the sealing orifice 410 by the buoyancy force of the biasing mechanism 416.

Once the liquid level in the drip chamber 404 reaches an operable fluid height 430, the valve 418 is forced away from the sealing orifice 410 to open the pressure activated valve 402. Specifically, the pressure head between sealing orifice 410 and the operable fluid height 430 is greater than the buoyancy force of the biasing mechanism 416, which opens the pressure activated valve 402.

In summary, an IV set according to the invention may include a pressure activated valve that opens when an operable liquid height is reached and closes when the liquid in the drip chamber falls below the operable liquid height. The operable liquid height is the height of liquid in the drip chamber that exerts pressure on the valve about equal to the force exerted by the biasing mechanism on the valve against the sealing orifice.

The pressure activated valve may be used to automatically prime the IV set, by controlling the flow of liquid through the IV set. For example, once the IV set is connected to a source of liquid, the drip chamber may be filled to an operable liquid height, when the liquid begins to flow from the drip chamber through the pressure activated valve and through the tubing of the IV set.

Additionally, the pressure activated valve permits the IV set to be uncoupled from a first source of liquid and be recoupled to a second source of liquid without having to reprime the IV set. More specifically the pressure activated valve closes once the liquid falls below the operable liquid height which prevents air from entering the tubing of the IV set through the drip chamber. Once reconnected to a source of liquid, the drip chamber fills with liquid to exceed the operable liquid height and the pressure activated reopens to allow liquid to flow.

The components of the pressure activated valve may be made from a variety of materials, such as metals, plastics, and ceramics. The components may be made by extrusion, injection molding, stamping, blow molding, machining, and other manufacturing processes known in the art.

The flow of the liquid may be retarded by using an air filter and positioning the first end of the tube near the drip chamber. A slow moving liquid may be less likely to entrap air in the IV set. Thus, less air may be entrapped and less time needed to remove air bubbles from the IV set before it may be connected to a patient.

The present invention may be embodied in other specific forms without departing from its structures, methods, or other essential characteristics as broadly described herein and claimed hereinafter. The described embodiments are to be considered in all respects only as illustrative, and not restrictive. The scope of the invention is, therefore, indicated by the appended claims, rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope. 

1. An IV set comprising: a drip chamber having an outlet orifice; and a pressure activated valve disposed proximate the outlet orifice of the drip chamber, the pressure activated valve comprising: a sealing orifice; a valve; and a biasing mechanism that biases the valve against the sealing orifice with a force less than the pressure head between the sealing orifice and an operable liquid height in the drip chamber to control the flow of liquid through the pressure activated valve.
 2. The IV set of claim 1, further comprising an air vent connected to the drip chamber.
 3. The IV set of claim 2, wherein the air vent is connected to a sidewall of the drip chamber proximate to the operable liquid height.
 4. The IV set of claim 1, wherein the biasing mechanism comprises a spring.
 5. The IV set of claim 1, wherein the biasing mechanism comprises a magnet.
 6. The IV set of claim 1, wherein the biasing mechanism comprises a flexible arm.
 7. The IV set of claim 1, further comprising a tube having a first end and a second end connected to the pressure activated valve, wherein the IV set further comprises a tube attachment device for disposing the first end of the tube proximate to the drip chamber.
 8. The IV set of claim 7, wherein the tube attachment device comprises a clip.
 9. The IV set of claim 7, wherein the tube attachment device comprises a magnet.
 10. The IV set of claim 7, wherein the tube attachment device comprises a hook and loop fastener.
 11. The IV set of claim 1, further comprising a tube having a first end and a second end connected to the pressure activated valve, wherein the IV set further comprises an end plug removably attached to the first end of the tube, wherein the end plug comprises an air vent.
 12. An IV set comprising: a drip chamber having an outlet orifice; and a pressure activated valve disposed proximate the outlet orifice of the drip chamber, the pressure activated valve comprising: a sealing orifice; a valve for closing the sealing orifice; and a means for biasing the valve against the sealing orifice with a force less than the pressure head between the sealing orifice and an operable liquid height in the drip chamber to control the flow of liquid through the pressure activated valve.
 13. The IV set of claim 12, further comprising an air vent connected to the drip chamber.
 14. The IV set of claim 13, wherein the air vent is attached to a sidewall of the drip chamber proximate to the operable liquid height.
 15. The IV set of claim 12, further comprising a tube having a first end and a second end connected to the pressure activated valve, wherein the IV set further comprises a tube attachment device for disposing the first end of the tube proximate to the drip chamber.
 16. The IV set of claim 12, further comprising a tube having a first end and a second end connected to the pressure activated valve, wherein the IV set further comprises an end plug removably attached to the first end of the tube, wherein the end plug comprises an air vent.
 17. A method for priming an IV set, the method comprising: connecting the IV set to a source of a liquid, wherein the IV set comprises a drip chamber having an outlet orifice; and a pressure activated valve disposed proximate the outlet orifice of the drip chamber, the pressure activated valve comprising a sealing orifice, a valve for closing the sealing orifice, and a biasing mechanism that biases the valve against the sealing orifice with a force less than the pressure head between the sealing orifice and an operable liquid height in the drip chamber to control the flow of liquid through the pressure activated valve; drawing the liquid into the drip chamber; and moving the valve from the sealing orifice to permit the liquid to exit the pressure activated valve when the head of the liquid in the drip chamber exceeds the force of the biasing mechanism.
 18. The method of claim 17, wherein the IV set further comprises a tube connected to the pressure activated valve having an end remote from the pressure activated valve and a tube attachment device, wherein the method further comprises the step of disposing the end of the tube proximate the drip chamber.
 19. The method of claim 17, wherein the IV set further comprises an air vent, the method further comprising the step of venting air from the drip chamber.
 20. The method of claim 19, wherein the air vent is disposed proximate the operable liquid height of the drip chamber, the method further comprising the step of preventing air from exiting the air vent when the height of the liquid within the drip chamber reaches the height of the air vent.
 21. The method of claim 17, further comprising the step of moving the valve against the sealing orifice to prevent the flow of liquid through the pressure activated valve when head of the liquid within the drip chamber is less than force of the biasing mechanism. 